Given the success and rapid spread of light therapy for SAD, clinical researchers immediately wondered how far the simple technology could be applied.  Multiple studies—although performed on a smaller scale than for SAD—covered a wide canvas, almost all with encouraging results.

Light therapy also worked for nonseasonal depression, even unremitting chronic depression that didn’t lift for years.  It worked for mothers who became depressed during pregnancy, offering the promise of a reprieve from potentially dangerous drug therapy.  Patients with attention deficit hyperactivity disorder, whether or not they were depressed, showed improvement in cognitive performance, along with a shift earlier in their circadian rhythms. Elderly, institutionalized patients showed mood improvement, and a slowing of cognitive decline.

REFERENCES

Reviews

Tunnainen A, Kripke DF, Endo T: Light therapy for non-seasonal depression (Cochrane Review). In: The Cochrane Library. Chichester, Wiley, 2004, vol. 2.
Even C, Schröder CM, Friedman S, Rouillon F. Efficacy of light therapy in nonseasonal depression: a systematic review. Journal of Affective Disorders 2008;108:11-23.

Studies

Lam RW, Carter D, Misri S, Kuan AJ, Yatham LN, Zis AP. A controlled study of light therapy in women with late luteal phase dysphoric disorder. Psychiatry Research 1999;86:185-192.
Lam RW, Levitt AJ, Levitan RD, Michalak EE, Cheung AH, Morehouse R, Ramasubbu R, Yatham LN, Tam EM. Efficacy of Bright Light Treatment, Fluoxetine, and the Combination in Patients With Nonseasonal Major Depressive Disorder: A Randomized Clinical Trial. JAMA Psychiatry. 2016;73(1):56-63.
Goel N, Terman M, Terman JS, Macchi MM, Stewart JW. Controlled trial of bright light and negative air ions for chronic depression. Psychological Medicine.2005;35:945-955.
Sit D, Wisner KL, Hanusa BH, Stull S, Terman M. Light therapy for bipolar disorder: A case series in women. Bipolar Disorders 2007;9:918-27.
Sit DK, McGowan J, Wiltrout C, Diler RS, Dills JJ, Liuther J, Yang A, Ciolino JD, Seltman H, Wisniewski SR, Terman M, Wisner KL. Adjunctive bright light therapy for bipolar depression: A randomized double-blind placebo-controlled trial. American Journal of Psychiatry, 175, 131-139.
Riemersma-van der Lek RF, Swaab DF, Twisk J, Hol EM, Hoogendijk WJ, Van Someren EJ. Effect of bright light and melatonin on cognitive and noncognitive function in elderly residents of group care facilities: a randomized controlled trial. Journal of the American Medical Association 2008;299:2642-2655.
Wirz-Justice A, Bader A, Frisch U, Stieglitz R-D, Alder J, Bitzer J, Hösli I, Jazbec S, Benedetti F, Terman M, Wisner KL, Riecher-Rössler A. (2011) A randomized, double-blind, placebo-controlled study of light therapy for antepartum depression. Journal of Clinical Psychiatry,72:986-993.